The present invention relates to an improved ablation catheter that is particularly useful for ablating in a tubular region of or near the heart.
Atrial fibrillation is a common sustained cardiac arrhythmia and a major cause of stroke. This condition is perpetuated by reentrant wavelets propagating in an abnormal atrial-tissue substrate. Various approaches have been developed to interrupt wavelets, including surgical or catheter-mediated atriotomy. A common procedure involves ablating a lesion to interrupt the wavelets using one or more electrodes mounted on the distal end of a generally-straight catheter. This procedure works well, for example, when ablating a line of block in the atria. However, for tubular regions in or around the heart, this procedure is less effective. For example, when the line of block is to be made about a circumference of the tubular region, it is difficult to manipulate and control the distal end of a straight catheter so that it effectively ablates about the circumference. Accordingly, a need exists for an improved catheter that is particularly useful for such applications.
The present invention is directed to a catheter having a generally-circular ablation assembly mounted on its distal end that carries a tip electrode. In one embodiment, the catheter comprises an elongated flexible tubular catheter body having an axis and proximal and distal ends. An ablation assembly is mounted at the distal end of the tubular body. The ablation assembly has a preformed generally circular curve that is generally transverse to the axis of the catheter body comprising a flexible tubing having proximal and distal ends and carrying a tip electrode at its distal end. An electrode lead wire extends through the catheter body and into the ablation assembly and has a distal end connected to the tip electrode.
In use, the distal end of the catheter is inserted into the heart of a patient. At least a portion of the outer circumference of the generally circular curve is contacted with the inner circumference of the tubular region so that the tip electrode is in a first position in contact with tissue along the inner circumference. The tip electrode is used to ablate tissue at the first position. The ablation assembly can then be rotated so that the tip electrode is in a second position in contact with tissue along the inner circumference different from the first position, and the tip electrode is used to ablate tissue at the second position. This procedure can be repeated to form a lesion of the desired length along the inner circumference. This design permits the user to have more control when ablating about a circumference of a tubular region in or around the heart, e.g., a pulmonary vein, the coronary sinus, the superior vena cava, or the pulmonary outflow tract.